Conventional orthopedic implants such as knee and hip implant systems have been in use for many years with considerable success. The use of custom designed implant components based on the patient-specific anatomy has moreover overcome many shortcomings of the older designs. Such patient-specific devices can be developed using commercially available software. Typically such devices are used for orthopedic interventions to the spine, hip, knee and/or radius. Patient-specific devices available on the market include patient-specific knee replacement prostheses, patient-specific femoral and tibial cutting blocks, distal radius drilling and cutting templates.
While patient-specific guides are now typically used to accurately place pins, guide bone cuts or insert implants during orthopedic procedures, the correct positioning of these patient-specific devices remains a critical factor with important impact on the outcome of the procedure.
Patient-specific devices are made according to a pre-operative plan formed from an MRI or CT scan of the patient and rely on the matching of an anatomical feature for correct positioning. Typically they contain at least one surface which mates specifically with the surface of the bone. They further contain one or more functional elements such as cylinders which guide the orientation of a drill or pin in the correct predetermined position in the bone.
While finding the correct position of the patient-specific devices may seem straightforward as the operator only needs to determine the correct patient-specific fit, it has often been observed that, minor discrepancies from the perfect fit will not be perceived by the operator. There are many causes for this, one of the most important being the presence of soft tissue which has not been entirely removed from the bone. The actual placement of the patient-specific device in the correct position is therefore not always that straightforward for the operator, leading to uncertainty for the operator and the possible incorrect placement of the patient-specific device, resulting in deviations from the surgical planning. As the best orthopedic results are achieved when the procedure occurs under the best circumstances, i.e. including not only the device being correctly positioned but also the operator being assured about the correct position of the patient-specific device, there is a need in the art for devices which allow to ensure that a patient-specific device is positioned correctly.
The present invention aims at providing methods and devices that make it possible to ensure the correct position of a patient-specific device, without a major additional burden for the operator during surgery.